ECTOPARASITICIDAL FORMULATION

Abstract: This invention relates to a method of treatment of ectoparasitically infested sheep comprising administering to a sheep a pour-on ectoparasiticidal formulation in a volume such that a desired ectoparasite kill rate as hereinbefore defined is achieved. In a second embodiment it also relates to a pour-on formulation effective against ectoparasites of sheep comprising an effective amount of at least one active agent and a non-lanolin dissolving solvent-carrier for said at least one active agent.

Description: ECTOPARASITICIDAL FORMULATION Technical Field This invention relates to formulations active against ectoparasites of animals and particularly to pour-on formulations active against ectoparasites of sheep, as well as to methods of treating such sheep against ectoparasite infestation. Background Art Traditionally sheep have been treated against infestation by ectoparasites such as lice or blow fly by dipping the sheep in an ectoparasiticidal formulation so that the animal is totally immersed. The difficulty with this method is that high volumes of the ectoparasiticidal formulation are necessary, that it is difficult to encourage the sheep to enter the dip and that it is both time consuming and physically demanding. A further disadvantage is that large volumes of the "dip" have then to be disposed of in an environmentally correct fashion. One alternative proposed to dipping animals is to apply an ectoparasiticidal formulation as a "pour-on", the formulation being applied locally, usually along the animal's backline, with the object that, by force of gravity, it spreads around the animal giving protection or treatment to all parts of the animal. One such formulation is disclosed in Australian Patent 563723 to Wellcome Australia Limited. This formulation comprises an anti-parasitic or insecticidal agent suspended or dispersed in an aqueous carrier. The difficulty with some prior art formulations is that the carrier dries out too quickly and does not allow the active agent to spread across the entirety of the animal's body. Thus untreated areas remain on the animal allowing the infestation to quickly return to the treated parts of the body. A number of Australian Patents including 77109/81 , 61113/90, 599383 and 31919/77 also disclose pour-on formulations. The difficulty with each of these disclosures is , however, that they relate to cattle and not to sheep. It must be appreciated that the fleece of a sheep whether in a shorn or unshorn form presents a unique set of problems in the treatment of ectoparasites; problems which are quite distinct from those of cattle hide. In particular, in unshorn sheep, the size and bulk of the fleece prevents the formulation being able to reach all parts of the animals body which might be infested, specifically in the brisket and neck region and in the lower parts of the body where infestation is usually high due to the warm, moist environment and its distance from the conventional backline location of application. The size and bulk of a fleece are particularly a problem if organo phosphorus compounds are used as the active agent since these compounds do not readily translocate. For this reason organophosphorus compounds are not commonly used as pour-on ectoparasiticides for sheep. Synthetic pyrethroids are becoming less effective as pour-on ecto¬ parasiticides since the vermin are developing resistance to the common synthetic pyrethroids used. The consequence of the growing resistance to pour-on formulations against ectoparasiticides based on synthetic pyrethroids is that they are increasingly ineffectual in eliminating infestation of sheep by ectoparasites. Because of the likely reinfestation of the animal subsequent to present treatments their economic benefit is limited. Desirably, such pour-on formulations should be 100% effective against the ectoparasite so that reinfestation is not such a rapid inevitability. The quality of the flock of sheep and thus the economic benefit therefrom can be greatly improved if a 100% kill rate can be achieved. It is thus an object of this invention to provide a pour-on formulation for treatment of ectoparasites jn sheep which achieves a desired kill rate, and preferably a 100% kill rate, by migration around the entirety of the animal's body. It is a further object of this invention to provide a method of treatment of sheep infested by ectoparasites, which method maximises the probability of migration of the active agent about the entire body surface of the animal. Summary of the Invention To this end, there is provided a pour-on formulation effective against ectoparasites of sheep comprising an effective amount of at least one active agent, and a non-lanolin dissolving solvent carrier for said at least one active agent. This invention is predicated upon the discovery that the reason many ectoparasiticidal formulations do not reach all parts of the animal's body is that they dissolve the lanolin of the sheep's fleece. Thus, on application, they dissolve the lanolin and become "locked" in the fleece preventing their seepage about the animal's body. It has been found that if a solvent-carrier is selected in which lanolin is not dispersible, the translocation of the active agent across the body of either a shorn or unshorn animal is greatly improved. Solvent-carriers which are most suitable for use in the formulations of the invention are those characterized as not being able to dissolve in lanolin at 30°C, and as having a viscosity low enough to enable translocation of the active agent around the body of a sheep to be treated. Desirably the carrier-solvent is also non-toxic. This latter characteristic is important in the treatment of sheep which are to be slaughtered for human consumption. Throughout this specification, the term "non-lanolin dissolving" is used with respect to solvent-carriers to mean those in which lanolin will not disperse at 30°C. Several families of solvent-carriers may be suited to the formulation of the invention including vegetable-based esters, co-solvents soluble in both water and oils and low viscosity kerosene-like solvents. In particular, the more preferred solvent-carriers are those which are vegetable-based esters, phthalates or derivatives thereof. Examples of suitable phthalates include dibutyl phthalate, di-2-ethylhexyl phthalate, di-iso-octyl phthalate, dimethyl phthalate.diethyl phthalate, di- isobutyl-phthalate, di-isodecyl phthalate or n-octyl n-decyl phthalate. Other suitable solvent-carriers include glyceryl tricaprylate caprate, peanut oil, sunflower oil, castor oil and PPG-15 stearyl ether. Active agents which might be incorporated into the formulation of the invention include synthetic pyrethroids, organo phosphorus compounds and insect growth regulators such as Vetrazin 1M (cyromazine). Because of the tendency of synthetic pyrethroids to dissolve in the oils released from the sheeps body after shearing, and because of the increasing resistance to synthetic pyrethroids of ectoparasites to be treated, the more preferred active agents are organo phosphorus compounds, exemplified by diazinon and propetamphos. Preferably, the formulations of the invention are formulated as emulsifiable concentrates. Purely aqueous formulations, it has been found, are less effective. The formulations of the invention may additionally include conventional excipients such as dyes, for example, Macrolex Yellow, Waxoline Yellow, surfactants such as, for example, Alkanate CS, Teric™, Kenmat™, emulsifiers, plasticizers, antioxidants, disinfectants and other conventional formulating agents. In formulations according to the invention, there may be present in the concentrated formulation 20-85% w/w of non-lanolin dissolving solvent-carrier, and 1.0-15.0% w/w of active agent. In a preferred embodiment of the invention, the concentrate formulation used is as follows: %w/w mass (g) Diazinon 90S Tech (active agent) 9.878 10.342 Teric 12A4 (surfactant) 1.958 2.050 Corflex 400 (di-butyl phthalate) 68.510 71.730 Alkanate CS (emulsifier) 9.452 9.896 Teric 200 (surfactant) 9.452 9.896 Waxoline Yellow 2GP-FW (dye) 0.750 0.785 TOTAL 100.000 104.699 Diluted 1 volume concentrate plus 6 volumes water as a working solution. The preferred formulation is as follows. Differences in national regulatory environments mean that different levels of residual sheep ectoparasite infestation are considered acceptable in different countries of the world. Thus, for example, in Australia, in order for a sheep to be acceptably treated, a 100% kill rate must be achieved, i.e. no ectoparasite must remain alive on the treated animal. However, in the United Kingdom, levels lower than 100% are considered acceptable treatment of infestation. "Desired kill rate" when used throughout this specification is thus defined as that of the national regulations of the country concerned. Thus in a second aspect of the invention, there is provided a method of treatment of sheep being ectoparasiticaUy infested comprising administering to a sheep pour-on ectoparasiticidal formulation, such as, for example, that described hereinabove, in a volume such that the desired kill rate is attained. The volume to be applied will vary according to the body surface area to weight ratio of the animal to be treated. For example, in Europe where animals are small in body surface area but nevertheless weighty, the preferred volume to be applied is one that is greater than 1.0 ml per kilo bodyweight of the sheep to be treated. In Australia, however, where sheep are larger in body surface area but no weightier than European sheep, the desired volume is one that is greater than 2.0 ml per kilo body weight of the sheep to be treated. This aspect of the invention is predicated on the discovery that reinfestation of sheep currently occurs basically as a result of untreated ectoparasites remaining in the brisket and remote regions of the animal. By increasing the volume of application (but not necessarily the concentration of active) it has been found that there is a stronger likelihood that the desired kill rate will be attained because the remote regions of the sheep are also treated. It will be appreciated that the upper limit of volume of emulsion applied will vary depending on the state of the fleece of the sheep. A heavily fleeced sheep will require a larger quantity of emulsion than a shorn sheep. It will also be appreciated that excess volumes applied will only result in substantial run-off and hence wastage, and thus should be avoided. Wherein the desired kill rate is defined by national regulation laws, in a preferred embodiment of the invention there is provided a method of treatment of sheep being ectoparasiticaUy infested comprising administering to a sheep a pour-on ectoparasiticidal formulation such as, for example, that described hereinabove, wherein the active agent is present in an amount such that when delivered in the desired formulation volume, the desired kill rate is attained. The concentration will vary with active and the resistance of the ectoparasite to be treated. For example, where the active agent is Diazinon, an organo phosphorus compound, the desired rate of application of the ectoparasiticidal formulation is about 40 mg/kg active agent delivered in a volume of about 3 ml per kilo body weight of the infested sheep. It will be appreciated that the necessary concentration of active will vary depending on its chemical nature. In the case of Propetamphos, the desired concentration is one which is greater than 15 mg/kg. The longer an animal remains infested with ectoparasites, the more likely its fleece will be damaged due to the tendency of the animal to rub against objects to relieve irritation caused by infestation. It is thus desirable to eradicate infestation in as rapid a period as possible. Thus in a third aspect of the invention, there is provided a method of treatment of sheep being ectoparasiticaUy infested comprising administering to a sheep a pour-on formulation, such as, for example, that described hereinabove in a volume such that the desired kill rate, as defined hereinabove, is substantially achieved within 14 days after treatment. Preferably the volume applied is greater than 2.0 ml per kilo body weight of the sheep to be treated. The formulations according to the invention can be applied to long- woolled (fully fleeced) or shorn sheep although it will be appreciated that since the formulation acts upon the skin of the sheep, to deliver the formulation to a fully fleeced sheep will require a considerable excess to allow for uptake of the formulation by the fleece itself. Further embodiments of the invention will now be described by way of example. The invention should not, however, be considered as being limited thereto. Calculations are based on the assumption that sheep are used having an average weight of approximately 50 kg and "success" is designated as a kill rate of 100% given that all tests were carried out under Australian and New Zealand conditions. Testing for ectoparasite infestation was carried out by counting the number of parasites present in 20 partings taken on each side of the sheep (40 partings in total). EXAMPLE 1 - POUR-ON LOUSICIDE EFFICIENCY AGAINST DAMALINIA EXAMPLE 1 A: An emulsion was formulated according to the following: Ingredient % w/w mass ( Diazinon (90.0%) 2.325 23.25 Teric 12A4 0.50 5.0 Macrolex Yellow 3G 0.10 1.0 Corflex 440 16.975 169.75 (di-isobutyl phthalate) Alkanate CS 2.5 25.0 Teric 200 2.5 25.0 BHA 0.1 1.0 Dl water 74.86 748.6 Nipastat 0.14 1.4 100.0 1000.0 The pour-on emulsion (Diazinon 2.1% w/w) was applied in a volume of 1.67 ml/kg body weight as a band commencing high on the neck of the sheep and finishing at the butt of the tail. Further bands were applied to either side of the initial stripe and partially overlapping the first until the appropriate volume was delivered. The treatment was applied immediately after shearing as follows: Ear Tag Weight Dose Vol Dose No (kg) (mis) (mg/kg) 232 27 45 35 177 25 40 33.6 212 33 55 35 187 33 55 35 203 30 50 35 208 25 Untreated Controls 181 27 Untreated Controls 241 32 Untreated Controls 246 21 Untreated Controls 219 30 Untreated Controls Treatments were administered using the Protector - dial a dose, drench/pour-on gun. Once treated, each group was penned separately in an electrified paddock where they were kept for the duration of the trial. Lice counts were performed pre-shearing, 7, 14, 21 , 28, 35 and 42 days after treatment, using the 20 partings per side technique. Results were calculated from the mean number of lice in each group. Percentage reduction of the lice count in the lice group was used as a correction factor. The formula used was as follows % reduction = 100 x (1-T 2 /C 2 x C-|/T*ι) Where T-i = pre treatment lice count of the treated group T = post-treatment lice count of the treated group C-i = pre-treatment lice count of the control group C 2 = post-treatment lice count of the control group Group Pre 7 DAT 14 DAT 21 DAT 28 DAT 35 DAT 42 DAT Shear Treated sheep 362.8 31.2 3.2 0.2 0.2 0.4 0 Control 353.4 306.2 31 1 244 196 200.8 166.4 % Reduction - 90 99 99.9 99.9 99.8 100 Eradication of the sheep body louse P. ovis was achieved at a kill rate of 100% after 42 days of treatment using the formulation of this example. EXAMPLE 1 B: To demonstrate the activity of active ingredients other than Diazinon, a formulation according to the following was prepared: Ingredient % w/w mass (g) Teric 12A4 1.958 78.32 Waxoline Yellow 2GP-FW 0.375 15.00 Corflex 400 73.824 2952.96 Alkanate CS 9.452 378.08 Teric 200 9.452 378.08 Propetamphos (90-91% w/w) 4.939 197.56 100.000 4000.00 The pour-on emulsion (diluted 1 :6) was applied in a volume of 3 ml/kg body weight in a manner similar to that described in Example 1A in a concentration of 20 mg/kg. Lice counts were performed pre-shearing 7, 14, 21 , 28, 35 and 42 days after treatment using the 20 partings per side technique. Using the calculation methods described in Example 1A the following results were achieved: Group Pre 7 DAT 14 DAT 21 DAT 28 DAT 35 DAT 42 DAT Shear Control 444.2 365.2 324.8 227.4 193.8 178.4 130.6 Treated sheep 435.8 0.8 0 0 0 0 0 % Reduction 99.8 100 100 100 100 100 Eradication of the sheep body louse P. ovis was achieved at a kill rate of 100% after only 14 days of treatment using the formulation of this example. COMPARISON EXAMPLE 1 - EXCLUSION OF PHTHALATE EXTENPER As a point of comparison with the formulations described in Example 1 , a formulation excluding the phthalate extender Corflex 440 (di-isobutyl phthalate) and in the absence of any other substitute extender, was prepared as follows: Ingredient % w/w mass (g. Piazinon (91%) 1.48 14.8 Teric 12A4 0.29 2.9 Macrolex Yellow 3G 0.1 1 1.1 Alkanate CS 1.40 14.0 Teric 200 1.40 14.0 Water 95.27 952.7 Orthophenylphenol 0.05 0.5 100.00 1000.0 The formulation was applied immediately after shearing in a manner as described in Example 1 and in a volume of 150 ml/50 kg sheep. Percentage reduction was calculated as in previous examples. Group Lice Counts Ear Tag Pre 7 PAT 14 PAT 21 PAT 28 PAT 35 PAT 42 PAT No Shearing 231 742 126 PIEP 43 365 286 1 10 39 20 21 3 41 347 253 135 51 26 17 7 52 298 125 41 5 3 3 7 97 260 205 104 90 70 104 50 Average 402.4 199 97.5 47.7 29.8 36.3 16.8 Kill rate 41.0% 73% 87.0% 91.2% 88% 94% CONTROLS 31 730 618 605 570 607 445 483 24 390 309 304 275 300 135 72 143 466 477 429 364 329 465 396 13 268 102 215 273 247 274 233 156 249 236 285 301 284 195 245 Average 420.6 348.4 367.6 396.6 353.4 302.8 284.6 It is clear that a satisfactory sustained kill rate was not achieved in the absence of a phthalate extender. COMPARISON EXAMPLE 2 - SUBSTITUTION OF PHTHALATE EXTENPER BY ALTERNATIVE EXTENDER IN WHICH LANOLIN IS SOLUBLE As a further point of comparison with the formulation described in Example 1 and to show the efficacy of an extender not soluble in lanolin, the following formulation was prepared: Ingredient % w/w mas$ (g) Diazinon (90.0%) 12.0 84.0 Teric 12A4 2.1 14.7 Macrolex Yellow 3G 0.8 5.6 Solvesso 150 (extender) 65.1 455.7 Alkanate CS 10.0 70.0 Teric 200 10.0 70.0 100.0 700.0 The formulation was emulsified in a concentrate:water ratio of 1 :3 such that the active was present in a concentration of 2.7% w/w. (Diazinon pour on concentrate 10.8% w/w) The emulsion was applied in a volume of 1.67 mlJkg body weight at the same time and in the same manner as described in Example 1 , according to the following: Ear Tag Weight Dose Vol Dose No (kg) (mL) (mg/kg) Y51 36 60 45.0 Y59 48 80 45.0 Y57 52 85 44.1 Y52 35 60 46.3 Y55 42 70 45.0 Y53 40 Untreated Controls Y54 39 Y60 46 Y58 37 Y56 41 Treatments were administered using the Protector dial a dose drench/pour-on gun. Once treated, each group was penned separately in an electrified paddock where they were kept for the duration of the trial. Lice counts were performed pre-shearing 7, 14, 21 , 28, 35 and 41 days after treatment using the 20 partings per side technique. The formula used was as follows % reduction = 100 (1-T 2 /C 2 x C 1 /T 1 ) Where T-i = pre treatment lice count of the treated group T 2 = post-treatment lice count of the treated group C-i = pre-treatment lice count of the control group C = post-treatment lice count of the control group Group Pre 7 DAT 14 DAT 21 DAT 28 DAT 35 PAT 41 PAT Shear Treated sheep 286.0 154.8 50.8 21.4 21.2 7.8 8.0 Control 281.4 250.4 245.0 227.0 189.2 196.8 157.4 % Reduction - 51.8 79.6 90.7 89.0 96.1 95.0 In the absence of a phthalate extender, using a conventional solvent - extender, Solvesso 150, as a replacement therefor, eradication of P. ovis to a degree sufficient for Australian Standards was nol achieved. EXAMPLE 2 - INCREASEP VOLUME OF APPLICATION To test whether or not increased volume of. application achieved a faster kill rate, an aqueous emulsion of Piazinon was prepared according to the following: Ingredient % w/w mass (a) Piazinon (910 g/kg) 1.67 25.05 Teric 12A4 0.29 4.35 Macrolex Yellow 3G 0.11 1.65 Corflex 440 9.0 135.0 Alkanate CS 1.4 21.0 Teric 200 1.4 21.0 Water 86.13 1291.95 100.00 1500.00 This formulation was applied in a volume of 3mUkg body weight of animal, the Piazinon being present in a concentration of 1.5% w/w, the dose rate being approximately 45 mg/kg. All sheep were treated in the same manner as described in Example 1 and immediately post-shearing. Ear Tag Treatment Weight PoseVol Pose No (kg) (mL) (mg/kg) 90 Test formulation 45 135 45.0 244 50 150 45.0 281 49 150 45.9 148 47 140 44.7 1 47 140 44.7 61 Control 46 _ . 46 46 - - 84 41 - - 88 43 - - 12 41 - - Treatments were applied using the NZ Protector dial-a-dose drench/pour- on gun. Once treated, each group was penned separately in electrified paddocks where they remained for the duration of the trial. Lice counts were performed pre-shearing 7, 14, 21 , 29, 35, 42, 49 and 57 dat using the 20 partings per side technique. Percentage reduction in lice counts was calculated using the change in lice counts for the control group as a correction factor. The formula used to calculate % reduction was the same as that used in Example 1 , with the following result: Mean Lice Counts - Pays after Treatment (PAT) Pre- 7 DAT 14 DAT 21 DAT 29 DAT 35 DAT 42 DAT 49 DAT 57DAT Shear Treated sheep 193.2 0.2 0 0 0 0 0.2 0 0 Control 185.0 100.8 72.0 50.4 58.8 56.6 52.6 48.4 43.0 % Red'n - 99.8 100.0 100.0 100.0 100.0 99.6 100.0 100.0 Eradication of the sheep body louse P. ovis was achieved after 14 days showing that increased volume of application gives more expedient results. EXAMPLE 3 - VARYING CONCENTRATION OF ACTIVE In order to determine the minimum effective concentration of active agent possible upon application of 150 mL/50 kg sheep, the following formulations were prepared: Base formulation Ingredient % w/w E ifl) Piazinon (91 %) 87.8 526 i Water } Macrolex Yellow 3G 0.1 1 Corflex 440 9.00 5 Alkanate CS 1 .40 l J Teric 200 1 .40 84.0 Teric 12A4 0.29 17.4 100.0 6000.0 Example 3A (40 mg/kg) (1.33% Piazinon w/w) base formulation 12.2 122.0 Piazinon (91 %) 1.47 14.7 water 86.33 863.3 100.0 1000.0 Example 3B (35 mg/kg) (1.16% Piazinon w/w) base formulation 12.2 122.0 Piazinon (91 %) 1.28 12.8 water 86.52 865.2 100.0 1000.0 Example 3C (30 mg/kg) (1.0% Piazinon w/w) base formulation 12.2 122.0 Diazinon (91 %) 1.10 11.0 water 86.70 867.0 100.0 1000.0 Example 3D (25 mg/kg) (0.83% Diazinon w/w) base formulation 12.2 122.0 Diazinon (91 %) 0.92 9.2 water 86.88 868.8 100.0 1000.0 Example 3E (20 mg/kg) (0.66% Diazinon w/w) base formulation 12.2 122.0 Diazinon (91 %) 0.73 7.3 water 87.07 870.7 100.0 1000.0 For each of Examples 3A-E, the treatments were applied immediately after shearing along the backline in 4-6 strips (depending on the volume to be applied. Details are as follows: Ear Tag Treatment Weight Dose Vol Dose No (kg) (mL) (mg/kg) 160 Example 3A 40 120 40 171 49 150 40 196 44 130 40 124 51 155 40 139 43 130 40 170 Example 3B 47 140 35 197 45 135 35 271 43 130 35 66 43 130 35 135 42 125 35 98 Example 3C 43 130 30 1 19 43 130 30 228 48 145 30 69 47 140 30 63 47 140 30 155 Example 3D 43 130 25 237 52 155 25 136 44 130 25 283 42 125 25 193 44 130 25 191 Example 3E 45 135 20 198 42 125 20 187 42 125 20 105 48 145 20 175 41 125 20 82 Control 44 . _ 149 49 - - 161 52 - - 166 47 - - 85 42 Treatments were applied using the NZ Protector dial-a-dose drench/pour- on gun. Once treated, each group was penned separately in electrified paddocks where they were kept for the duration of the trial. Lice counts were performed pre-shearing 7, 14, 21 , 28, 35 and 42 days after treatment using the 20 partings per side technique. Percentage reduction in lice counts was calculated using the change in lice counts for the control group as a correction factor, using the formula given in example 1. Mean Lice Counts - Days After Treatment (DAT) Pre- 7 DAT 14 DAT 20 DAT 28 DAT 35 DAT 42 DAT Shear Lice Count Example 3A Treated Sheep 163.8 42.4 19.6 6.4 3.4 2.6 0 Control 141.2 66.8 112.8 92.6 73.8 81.8 58.8 % Red'n 45.3 85.1 94.1 96.0 97.3 100.0 Example 3B Treated Sheep 161.2 1.2 0.4 0 0 0 0 Control 141.2 66.8 1 12.8 92.6 73.8 81.8 58.8 % Red'n 98.4 99.7 100.0 100.0 100.0 100.0 Example 3C Treated Sheep 150.8 14.6 2.4 0.8 0.8 0.6 0 Control 141.2 66.8 1 12.8 92.6 73.8 81.8 58.8 % Red'n 79.6 98.0 99.2 98.9 99.3 100.0 Example 3D Treated Sheep 143.8 212.8 7.6 0.2 3.2 3.8 1.8 Control 141.2 66.8 112.8 92.6 73.8 81.8 58.8 % Red'n 66.6 93.4 99.8 95.8 95.5 97.1 Example 3E Treated Sheep 140.2 5.2 1.2 0.2 0 0 0.2 Control 141.2 66.8 1 12.8 92.6 73.8 81.8 58.8 % Red'n 92.2 98.9 99.8 100.0 100.0 99.7 Eradication of sheep body louse was achieved at 42 days using formulations 3A, 3B and 3C. Thus it is clear that these formulations are effective in achieving 100% kill rate, although higher concentrations are likely to give more expedient results, i.e. 100% kill in a lesser period of time. In the Example 3A group, one animal was responsible for the delay in achieving 100% efficacy. The counts at 7, 14, 21 , 28, 35 and 42 days post- treatment were 185, 94, 31 , 17, 13 and 0 respectively. This sheep was extremely heavily infested and was difficult to shear; i.e. tufts of wool were present at treatment. Similar tests using concentrations of Diazinon firstly at 15 mg/kg (0.5% w/w) and secondly at 10 mg/kg (0.33% w/w) failed to eradicate the sheep body louse P. ovis. EXAMPLE 4 - COMPARISON OF PHTHALATE EXTENDERS To show that phthalate extenders other than di-isobutyl phthalate are effective for the purposes of the invention, the following formulations were prepared: EXAMPLE 4A Ingredient % w/w mass (g) Piazinon (91%) 1.47 16.17 Teric 12A4 0.29 3.19 Macrolex Yellow 3G 0.1 1 1.21 Corflex 400 (di-butyl phthalate) 9.00 3.0 Alkanate CS 1.40 .5.4 Teric 200 1.40 14.0 Peionised Water 86.28 949.08 Orthophenylphenol 0.05 0.55 100.00 1 100.0 (1.33% Piazinon w/w; dose = 3.0 mlJkg ≡ 40 mg/kg) EXAMPLE 4B Ingredient % w/w mass (g . Diazinon (91%) 1.47 16.17 Teric 12A4 0.29 3.19 Macrolex Yellow 3G 0.11 1.21 DIBP (di-isobutyl phthalate) 9.00 99.00 Alkanate CS 1.40 15.40 Teric 200 1.40 15.40 Deionised Water 86.28 949.08 Orthophenylphenol 0.05 0.55 100.0 1 100.0 (1.33% Diazinon w/w; dose = 3.0 rπlJkg ≡ 40 mg/kg) All sheep were treated immediately after shearing according to the manner described in Example 1. No control group was used. Ear Tag Treatment Weight Dose Vol Dose No (kg) (mL) (mg/kg) 263 Example 4A 27 80 39.4 201 39 1 15 39.2 279 33 100 40.3 95 37 1 10 39.5 61 41 125 40.6 227 Example 4B 34 100 39.1 242 30 90 39.9 205 34 100 39.1 125 34 100 39.1 46 40 120 39.9 Treatments were applied using the NZ Protector dial-a-dose drench pour- on gun. Once treated, each group was penned separately under cover for 9 days, after which they were penned outside in electrified paddocks where they were kept for the duration of the trial. Lice counts were performed pre-shearing, 7, 14, 21 , 28, 35 and 43 DAT using the 20 partings per side technique. Percentage lice reductions were calculated by dividing the average pre- shearing lice count into the average weekly lice count for that group. Group Mean Lice Counts Pre- 7 DAT 14 DAT 21 DAT 28 DAT 35 DAT 43 DAT Shear Example 4A Treated Sheep 353.6 27.0 6.8 3.0 1.60 0.2 0 % Red'n 92.0 98.0 99.0 99.5 99.9 100 Example 4B Treated Sheep 348.6 14.2 4.6 0 0 0 0.2 % Red'n 95.9 98.6 100 100 100 99.9 It is evident from these results that the formulations of Examples 4A and 4B are equivalent showing that dibutyl phthalate is an acceptable substitute for di-isobutyl phthalate. EXAMPLE 5 - FIELD TESTS To determine large scale efficacy of formulations according to the invention a formulation was prepared as follows: Ingredient % w/w mass (g) Diazinon 90S (Technical) (90.5%) 9.878 29.634 Teric 12A4 1.958 5.874 Macrolex Yellow 3G 0.743 2.229 Corflex 400 (dibutyl phthalate) 68.517 205.551 Kemmat SC15 9.452 28.356 Teric 200 9.452 28.356 100.000 300.000 (diluted to 1 vol. cone: 6 vol water to give Diazinon 1.33% w/w) Formulation was applied to sheep using a Magrath electric hand wand using 10 cm perforated brass "T" piece screw on nozzle. A total of 901 sheep were treated immediately off shears as follows: Prior to shearing, 25 2V 2 - 5V 2 year old merino ewes were randomly selected, ear tagged and counted for lice. A post-shearing lice count was then conducted. The sheep were then weighed and dosed immediately after shearing according to the weight of the heaviest sheep in each mob i.e., BODY WEIGHT - KG DOSE VOLUME - mL 0-30 90 31 -40 120 41 -50 150 51 -60 180 61 -70 210 71 -75 225 Sheep in excess of 75 kg body weight to be dosed at 3.0 mL per kg live weight. The appropriate dose was applied to the backline of each sheep in the mob in a single unbroken band approximately 120 mm wide, extending from behind the ears through to the butt of the tail. TABLE 1 MOB NO. HEAVIEST B/W DOSE VOL TREATED RECORDED (Shorn) (mL) (kg) Weaners 159 47 150 1 2 y/o ewes 1 13 55 180 2V 2 - 5V 2 y/o ewes 601 57 180 2V 2 y/o wethers 28 65 210 Lice counts were performed using the 20 partings per side technique as follows: Pre-shearing 25 eartag sheep Post-shearing 25 eartag sheep 34 PAT 25 eartag sheep + 25 others at random * 85 PAT 25 eartag sheep + 25 others at random * 134 PAT 25 eartag sheep + 25 others at random * 190 PAT 25 eartag sheep + 25 others at random * * Any sheep showing signs of rubbing are to be included in this group of 25. The average number of lice found per sheep in each group was as follows: TABLE 2 Pre- Post- 34 PAT 85 PAT 134 PAT 190 PAT Shear Shear 25 Eartag sheep 146.6 71.7 0 0 0 0 25 Others 0 0 0 0 Evidently eradication of P. ovis was achieved using the formulation of this example. No lice were found at subsequent inspections. EXAMPLE 6 - PEGREE OF TRANSLOCATION To determine the degree and speed of translocation of the formulation of the invention over the body surface of a sheep after trea* ~ nt, the following formulation was prepared and administered: %w/w mass (g) Piazinon 90S Tech 9.878 3.75 Teric 12A4 1.958 0.74 Corflex 400 68.510 26.04 Kenmat 9.452 3.59 Teric 200 9.452 3.59 Waxoline Yellow 2GP-FW 0.750 0.29 100.000 38.00 (diluted 1 :6 by volume to give Piazinon 1.33% w/w) A 3 year old merino was shorn, weighed and treated immediately with the diazinon spray-on. It had not received any insecticide treatment for 12 months. The sheep weighed 37 kg and was treated with 110mL of the product. A wide band was applied from high on the neck, behind the ears, to the butt of the tail at a dosage rate of 3mL per kg bodyweight. The animal was hand restrained during treatment and placed under cover in a pen with mesh floor and sides for the duration of the trial. Puring and after treatment, the sheep had no contact with other treated animals and was not exposed to any rain. On advice from the State Chemistry Laboratory, Pepartment of Agriculture, Victoria, approximately 2cm square scrapings of wool and skin were taken as follows: PAYSO 15 minutes after treatment & PAYS 1.3.7 2 samples, left and right in the middle of the back and in the band of product. PAYS 1,3, 7 Mid-line - half way from the backline to the bellyline, at the line of the shoulder, mid-flank and rump ie., 6 samples at each time period. This was repeated on the other side of the body ie., 12 samples in total. DAYS1.3.7 Bellyline - at the line of the shoulder, mid-flank and rump on both sides ie., 12 samples at each time period. PAYS 1.3.7 A scraping was taken from the neck/brisket area, in the mid- line - see above diagram. Care was taken in positioning the scrapings eg., left bellyline shoulder sample was exactly vertically below the mid-line shoulder sample at day 1 , so that samples at days 3 and 7 were minimally affected by variations in diazinon spread caused by bare patches above the lower samples at days 3 and 7. A new scalpel blade was used for each scraping site. Tables 3, 4 and 5 show the levels of diazinon detected at each test point throughout the trial. Table 3 - DIAZINON (PPM) - WHOLE WOOL DAYS POST BACKLINE MID-LINE LEFT TREATMENT LEFT RIGHT SHOULDER FLANK RUMP 0 21 ,000 16,000 1 19,000 19,000 1400 84 940 3 15,000 16,000 1 100 220 170 7 21 ,000 17,000 730 1 90 590 DAYS POST MID-LINE RIGHT BELLY-LINE LEFT TREATMENT SHOULDER FLANK RUMP SHOULDER FLANK RUMP 0 1 290 230 470 1 80 1 50 890 3 320 1 70 480 140 360 54 7 210 1 10 390 290 150 420 DAYS POST BELLY-LINE RIGHT NECK TREATMENT SHOULDER FLANK RUMP 0 1 430 87 53 230 3 210 54 73 220 7 530 52 65 1 70 Table 4 - DIAZINON (PPM) - WHOLE WOOL DAYS POST MIDLINE BELLY-LINE TREATMENT MEAN RANGE MEAN RANGE 1 569 84-1400 298 53-890 3 410 170-1100 148.5 54-360 7 370 1 10-730 251.2 52-530 Table 5 - DIAZINON (PPM) - WHOLE WOOL (MEAN VALUES) DAYS POST MIDLINE BELLY-LINE TREATMENT LEFT RIGHT LEFT RIGHT 1 808 330 407 190 3 496 323 185 1 12 7 503 237 287 216 The values (PPM diazinon) are reported on a whole wool basis. The laboratory determined the percentage wool grease on 3 samples - 16.11 %, 21.5% and 17.6% w/w. The approximate concentration in wool grease can be calculated on the basis of the average wool grease content of the wool is 18.4% w/w ie., multiply the individual results by a factor of 5.4. Due to difficulties in handling the trial animal, the band applied did deviate somewhat to the left side of the mid-line. However, this would be seen in a commercial situation on some sheep and highlights the worth of a wide band of product being applied. The levels detected on the right belly-line at the flank and rump levels for days 1 , 3 and 7 demonstrate the effect of the deviation of the band to the left. However, there was still ample coverage of this right side eg., Day 1 , "belly-line right rump" 53 PPM diazinon in whole wool, or 286 PPM in the wool grease and presumably the skin fats and oils, where the lice live and breed. Particular note is made of the fact that levels detected in the neck/brisket region at all stages was high illustrating the ability of the formulation to translocate across the entire animal. A wide variation in the range of diazinon levels is noted; translocation would be affected by length of wool after shearing, conditions of the skin, wool follicle density, wool and skin grease levels and the level applied at the back¬ line. At day 7, this range had tightened considerably. EXAMPLE 7 - LONG-WOOLLED SHEEP The following trials conducted in New Zealand demonstrate that the formulations according to the invention may also be useful against ectoparasite infestation of long-woolled sheep. The following formulation was prepared and administered to Romney/Border Leicester ewes having 10-12 cm of wool growth. %w/w mass (kg) Piazinon 90S Technical 9.878 29.634 Teric 12A4 1.958 5.874 Macro-lex Yellow 3G 0.743 2.229 Corflex 400 68.517 205.551 Kenmat SC15 9.452 28.356 Teric 200 9.452 28.356 TOTAL 100.000 300.700 (diluted 1 :6 by volume to give Piazinon 1.33% w/w : rate = 3ml/kg) The ewes were sprayed along the backline using a. t otector gun and narrow nozzle. The treatment extended from the base of the neck to the rump in a 15 cm wide band. The following results were achieved when a procedure of counting the lice in a 10 cm parting of wool at 10 sites around the body (being the brisket, neck, lower and upper shoulders and withers on each side of the body) was adopted. Ear Tag Weight Pose Vol Louse Scores No. (kg) (mis) P.A.T. 0 21 41 370 67 201 9 3 0 371 80 240 1 1 0 0 372 78 234 1 1 1 0 373 53 165 17 D - 374 73 219 13 L 0 375 73 219 7 0 0 497 67 201 62 1 0 498 78 234 35 0 0 499 85 255 21 0 0 500 80 240 45 1 0 Thus a 97.4% reduction was achieved 21 days post-treatment and 100% reduction was achieved 41 days post-treatment. EXAMPLE 8 - RAIN AFFECTED TREATMENT A further advantage of the formulations according to the invention is that they appear to be unaffected by post-treatment rain. The following example illustrates the efficacy of a formulation according to the invention applied to sheep 4 hours prior to heavy rain. The following formulation was prepared and administered to romney sheep having 2.5-4.0 cm wool growth. %w/w mass (kg) Diazinon 90S Technical (9051 ) 9.878 29.634 Teric 12A4 1.958 5.874 Macro-lex Yellow 3G 0.743 2.229 Corflex 400 68.517 205.551 Kenmat SC15 9.452 28.356 TOTAL 100.000 300.700 (diluted 1 :5 : application rate 3ml/kg, 45 mg/kg) Results achieved were as follows: Group % reduction in lice numbers weeks post-treatment 1 2 3 4 5 6 Treated sheep 100 100 100 100 100 100 Control 15.5 15.4 41.5 65.3 28.0 41.5 Thus, despite heavy rain post-treatment, formulations according to the invention were effective in eradicating lice infestations. In such weather conditions, sheep are not usually re-treated and this can result in failure to eradiate lice. It is evident from the above that inclusion of a phthalate extender in pour- on formulations based on organo phosphorus compounds gives substantial advantages over prior art formulations used to treat ectoparasiticidal infestation in sheep. Furthermore, it is evident that application of such formulations in volumes greater than 2.0 ml_/kg body weight of animal also achieves substantially improved effects over prior art formulations designed to ectoparasiticidally treat sheep. Whilst this invention has been described with respect to Damalinia Ovis: sheep lice, it may also be active against other ectoparasites such as blowfly. Thus the invention should be seen as being not restricted to the particular ectoparasites upon which trials have been conducted. It will be understood that this invention is not limited to the specific embodiments described herein but that substitutions particularly of chemical alternatives may be carried out whilst the core of the invention remains the same.

Claims: THF OI AIMS DFF1NING THE INVENTION ARE AS FOLLOWS: 1. A method of treatment of ectoparasiticaUy infested sheep comprising administering to a sheep a pour-on ectoparasiticidal formulation in a volume such that a desired ectoparasite kill rate as hereinbefore defined is achieved. 2. A method according to claim 1 wherein the volume of ectoparasiticidal formulation administered is greater than 1.0 ml per kilo bodyweight of a sheep to be treated. 3. A method according to one of claims 1 or 2 wherein the volume of ectoparasiticidal formulation administered is greater than 2.0 ml per kilo bodyweight of a sheep to be treated. 4. A method according to any one of claims 1 to 3 wherein the desired ectoparasite kill rate is 100%. 5. A pour-on formulation effective against ectoparasites of sheep comprising an effective amount of at least one active agent and a non-lanolin dissolving solvent-carrier for said at least one active agent. 6. A pour-on formulation as claimed in claim 5 wherein said active agent and said non-lanolin dissolving solvent-carrier are present in amounts such that the formulation is effective against ectoparasites when delivered in a volume of greater than 1.0 ml per kilo bodyweight of a sheep to be treated. 7. A pour-on formulation as claimed in claims 5 or 6 wherein said non- lanolin dissolving solvent-carrier is selected from the group consisting of vegetable based esters, phthalates, co-solvents soluble in both water and oils and low viscosity kerosene-like solvents. 8. A pour-on formulation as claimed in any one of claims 5-7 wherein said non-lanolin dissolving solvent-carrier is a phthalate. 9. A pour-on formulation as claimed in any one of claims 5-8 wherein said active agent is present in an amount of 1 -15% w/w and said non-lanolin dissolving solvent-carrier is present in an amount of 20-85% w/w. 10. A pour-on formulation as claimed in any one of claims 5-9 wherein said active agent is an organophosphorous compound. 11. A method of treatment of ectoparasiticaUy infested sheep comprising administering to a sheep a pour-on ectoparasiticidal formulation comprising an organophosphorus active agent and a non-lanolin dissolving solvent carrier. 12. A method according to claim 11 wherein said non-lanolin dissolving solvent-carrier is selected from the group consisting of vegetable based esters, phthalates, co-solvents soluble in both water and oils and low viscosity kerosene-like solvents. 13. A method according to claims 1 1 or 12 wherein said non-lanolin dissolving solvent-carrier is a phthalate.

Inventors: HALLS NEIL GRAHAM, KLOSE JOHN BARRY, HALLS, NEIL, GRAHAM, KLOSE, JOHN, BARRY
Applicants: GRAMPIAN PHARM LTD, HALLS NEIL GRAHAM, KLOSE JOHN BARRY, SOLTEC RES PTY LTD, GRAMPIAN PHARMACEUTICALS LTD., HALLS, NEIL, GRAHAM, KLOSE, JOHN, BARRY, SOLTEC RESEARCH PTY. LTD.
Application year: 1994
Main classification: A61K47
IPC codes: A01N25, A61K9